4l8 BKAIN MECHANISMS AND LEARNINC 



By means of an objective technique consisting of hypnotic mduction, 

 we have recently observed in humans that a synchronized EEG is recorded 

 during the somnambuhst phase of suggested sleep, showing thcta and 

 even delta rhythms. If a verbal contact is established with the hypnotized 

 subject, it may be observed that he answers when his EEG pattern 

 resembles those recorded during the waking state with closed eyes. 

 Spontaneous post-hypnotic amnesia for the meannigful conversation is 

 shown by the subject (Dittborn, Borlone and Palestini, 1959). 



The desynchronized EEG patterns in MPP animals do not enable it to 

 be niferred that they are in a waking state. But the fact that these animals 

 have a normal pupil and can still make vertical eye movements, make it 

 possible to study some behavioural reactions. In fact, they have shown the 

 capacity to make an apparently directed or intentional movement with 



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OLF STIM 



I 1 I 1,1 I 1 I I 



.5sec 



Fig. 2 



Effect of heterosensory stimulation on visual potentials (MPP) 



EEG record. Primary potentials decrease during olfactory extrastimulation. 



their eyes to follow an object passing across their visual fields. Movements 

 disappear as soon as synchronized EEG patterns are seen, while the pupil 

 becomes myotic. A more important reaction is the pupil dilatation which 

 appears in some cats with midpontnic section when a more emotionally 

 significant stimulus is presented to them (rat, dog). 



In order to obtain further information about waking behaviour in the 

 MPP we have been studying 'attention' in these animals (Palestini, 

 Lifschitz and Armengol, 1959). In some, the cortical potentials evoked by 

 a flash decreased when the MPP was submitted to a simultaneous hetero- 

 sensory stimulation (olfactory). Of course, these results were obtained 

 during a desynchronized pattern of activity which apparently was not 

 modified during the process of attention (Fig. 2). This result, compared 

 with controls, enabled us to conclude that the MPP would be able to 

 develop an alert state resembling that of a normal animal. 



